In the related art, in order to shield the harmful electromagnetic wave from the PDP, a mesh pattern that is made of a copper material is manufactured by using a photolithography process. However, since the photolithography process is complicated and the cost of the raw material is high, the production cost is high and is most costly in respects to raw material of the PDP filter. However, since the competition of PDPs and LCDs is deepened in a FPD (Flat Panel Display) market, it is required to develop a low-priced raw material, and a technology has been developed to print a mesh pattern by using a conductive paste through a printing process such as a screen printing process, an offset printing process or the like.
It is necessary to sufficiently reduce the specific resistance of the conductive paste that is used to perform the printing so that the characteristics of the electromagnetic interference shield film produced by using the printing process are sufficiently realized.
In order to achieve this, the use of the conductive paste comprising the metal powder has been developed. However, when the conductive pattern is printed by using conductive paste according to the offset printing process, light from the PDP and external light is reflected due to a gloss of metal, which negatively affects contrast. Therefore, there is a need to perform the blackening treatment of the conductive pattern.